No-volt tripping mechanism for electrical switches



Aug. 30, 1932. F. J. PAVITT 1,874,797

NO-VOLT TRIPPING MECHANISM FOR ELESTRICAL SWITCHES Filed Jan. 21. 1930 Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE FREDERICK JAMES PAVITT, OF BRIGHTON, ENGLAND Application filed January 21, 1980, Serial No. 422,388, and in Great Britain January 25, 1929.

This invention relates to, and has for its object the provision of improvements in, control apparatus for electric circuits.

The invention consists broadly in the combination of a winding, an armature controlled thereby, a switch having an operative position at which said winding is adapted to be energized, and an interlock between said switch and said armature whereby said armature is held at the attracted position independently of said winding until said switch is actuated to the operative position whereupon said armature is left free to move from said attracted position upon said winding becoming de-energized independently of said switch.

In order that the invention may be the more clearly understood an apparatus in accordance therewith will now be described 29 reference being made to the accompanying somewhat diagrammatic drawing, wherev Figure 1 is an elevation of said apparatus looking from left of Figure 2.

Figure 2 is a side elevation of the same looking from the right of Figure 1.

Referring to this drawing the numeral 1 designates a shaft on which are mounted the moving elements of a line switch. This shaft has an arm 2 rigidly mounted thereon and a lever 3 oscillatably mounted thereon. The lever 3 is biassed in a counter clockwise direction (according to Figure 2) by means of a spring 4 having one end secured to an end of said lever and the other end secured to a fixed pivot 5, and by virtue of this bias the other end of said lever presses against a laterally projecting pin 6 carried by said arm 2 and tends thereby to move the switch to the open position. The switch when closed (as in the drawing) is retained, in opposition to this bias by means of a catch 7 pivotable about a pivot 7a and formed as shown so as to be adapted to engage a second lateral pin 8 on said arm 2 and thereby positively retain said arm 2 at the switch closed position until moved in a counter clockwise direction.

Connected in the circuit controlled by said switch is a no-volt winding 9 having an associated armature 10 pivoted about a fixed pivot 11. A lug 10a extends rigidly from said armature beyond said pivot 11 and at its end is pivotally connected at 12a to a longitudinally slidable rod 12. This rod 12 is biassed by means of a light spring 13 in an upward direction (according to the drawing) and thus the armature 10 is permanently biassed from the attracted position shown in full lines to the unattracted position shown in dotted lines. The lower end of each rod 12 is of reduced section and bent over at a right angle, and the bent over portion engages under one end of a bell crank lever 14 oscillatable about the pivot 5. The other end of said lever 14 is formed with a shoulder which when the armature 10 is at the attracted position supports the bent over end of a tripping lever 15 pivoted about a pivot 16. When however the armature moves from the attracted position the rod 12 moves upwards thereby rotating the lever 14 in a counter clockwise direction so that the end of the lever 15 is released. This end of said lever 15 is much further than the other end from the pivot 16 and therefore upon release said lever 15 rotates by gravity and/or by spring bias round its pivot in a counter clockwise direction. The remote end of said lever 15 carries an enlarged hammer head 17 which upon said lever rotating as stated is adapted to strike the catch 7 a hammer blow thereby knocking it round in a counter clockwise direction and releasing the arm 2 whereupon the switch opens under the influence of the spring 4, and a torsion spring acting on the switch shaft 1 through the medium of the pin 6. It will be observed that owing to the relatively large distance from the pivot 16 of the turned over end of the lever 15, a considerable moment about the pivot 16 will only exert a very slight pressure of the bent over end on the shoulder on the lever 14, and therefore the force necessary to move said lever 14: from said bent over end will be small consistently with said hammer head 17 making an impact of considerable magnitude against the catch 6. It is thus possible to make the bias tending to release the armature 10 very light consistently with the tripping lever 15 being certain in its action.

from the non-attracted position. 'The ar rangement is such that in closing the switch, contact is actually established just before the pin 18 leaves the pin 19. Thus the armature 1O isheld at the attracted position until cir cuit connections are established, immediately after which it is free, upon voltage failure, to move to the unattracted position thereby effecting the tripping of the catch 6 and reopening the switch.

From the above the function of the device will have been clear. The switch being at the closed position and the armature be- 7, ing attracted as shown, upon failure of voltage said armature will fall away to the position shown in dotted lines, thereby tripping the catch 7, and permitting the switch to 7 open. Opening of the switch will then by the mechanical interlock above described imv mediately effect return of the armature 10 to the attracted position. Upon reclosure of the switch the armature will be left free to fall away upon the voltage again failing.

, During closure of the switch the catch 7 and lever will be reset to the position shown either automatically or by hand.

If desired an overload device may also be provided adapted upon the occurrence of M overload to effect the rotation of the lever 14 in a counter clockwise direction and thereby trip the catch 7 and effect the opening of the switch in the same manner as in the case of voltage failure. 7

What I claimand desire to secure by Letters Patent is 1. A control apparatusfor electric circuits comprising a winding, an armature controlled thereby, a moving element having an opera-' tive position at which said winding is adapted I to be energized, an interlock between said element and said armature whereby said armature is held at the attracted position in-.

dependently of said Winding until said element is actuated to the operative position whereupon said armature is left free to move from said attracted position upon said windingbecoming de-e-nergized independently of the movement of said element, a latch adapted to retain said element at said operative position and means whereby upon release of said armature said latch is adapted to be tripped for allowing the element to move to' the inoperative position the tripping of said latch be-' ing'effected by a hammer blow imparted by.

therelease of energy other than that stored by the movement of the armature to the attracted position. I

2. A control apparatus for electric circuits comprising a winding, an armature controlled thereby, a moving element having an operative position at which said winding is adapted to be energized, an interlock between said element and said armature whereby said armature is held at the attracted position independently of said winding until said element is actuated to the operative position whereupon said armature is left free to move from said attracted position upon said winding becoming de-energized independently of the movement of said element, a latch adapted to retain said element at said operative position means whereby upon release of said armature said latch is adapted to be tripped for. allowing the element to move to the inoperative position the tripping of said latch being effected by a hammer blow imparted by the release of energy other than that stored by the movement of the armature to theattracted position and a second Winding upon energization of which said latch is adapted to be tripped by release of thesame energy imparting the hammer blow.

3. A control apparatus for electric circuits comprising a winding, an armature controlled thereby, a moving element having an operative position at which said winding is adapted to be energized, an interlock between said element and said armature whereby said armature is held at the attracted position 1ndependently of said winding until said element is actuated to the operatlve position whereupon said armature is left free to move from said attracted position upon said Winding becoming deeenergized independently of the movement of said element, a latch adapted to retain said element at said operative position, a biased tripping means, acatch retaining said means and adapted to release said means upon movement of said armature, said tripping means upon release being adapted to trip said latch with a hammer blow, thereby allowing the element to move to the inoperative position.

FREDERICK JAMES PAVITT. 

